1. Field of the Invention
This invention relates to a composition of matter useful as a polishing agent in a dentifrice and to a dentifrice, preferably a toothpaste, which effectively cleans and polishes teeth without a high degree of abrasion and scratching.
2. Description of the Relevant Art
Dentifrices are used to clean teeth. In particular, a toothpaste is preferably brushed daily against the teeth with a toothbrush. A toothpaste aids in the removal of food particles, the removal of discoloration caused by substances such as tobacco or tea, and the removal of firmly adhering bacterial films, referred to as plaque, from the surface of teeth. In addition to removing substances from the surface of teeth, toothpastes also polish teeth. Both cleaning and polishing are effected by (1) abrasive substances, referred to herein as polishes, which are present in the toothpaste and, (2) to a lesser extent, surfactants which are contained in the toothpaste.
To achieve cleaning and polishing, the polishes have to provide a certain degree of abrasiveness with respect to the surface of the teeth. It is important, however, that abrasiveness with respect to dental enamel and dentine be at an acceptably low level to prevent the surface of the teeth from being damaged by the daily use of the toothpaste. Not only should the polishes in the toothpaste avoid producing any deep scratches on the surface of the teeth, but also the polishes should in fact assist in smoothing out any roughness there may be on the surface of the teeth.
A suitable polish should of course also be compatible with the other components of the toothpaste. It should lend itself to processing with water, humectants and consistency regulators to form a ductile paste readily dispensable from tubes or dispensers and should not adversely affect known caries inhibitors, for example fluoride carriers, such as NaF or Na monofluorophosphate, even in the event of prolonged storage.
As illustrated in U.S. Pat. No. 3,957,968, toothpastes containing a combination of alpha-aluminum oxide (corundum) and a polish having a Mohs hardness of less than about 6 are said to have good cleaning and polishing effects. Alpha-aluminum oxide, however, has a relatively strong abrasive effect on dental enamel. To reduce the enamel abrasion, certain calcium, magnesium or sodium salts have been added to a dentifrice containing alpha-aluminum oxide polishes and a hydrated silicious abrasive, with or without raising the pH of the dentifrice to a value above 7, as shown in U.S. Pat. No. 4,144,322. According to U.S. Pat. No. 4,060,599, alpha-aluminum oxide is used in a mean ultimate crystalline particle size of about 1 to 2 microns.
The above-mentioned measures have not completely solved the problem of the excessive abrasion of dental enamel and the excessive scratching effects associated with known polishes. Workers in the art have continued to search for dentifrices containing polishing agents which have reduced abrasion of dental enamel and reduced scratching effects.
Accordingly, an object of the present invention is to provide suitable polishing agents or polishing agent combinations which, although achieving an optimal cleaning and decoloring effect on the surface of teeth, can have only a mild abrasive and scratching effect.
Another object of the invention is to provide a suitable carrier for such polishing agents which makes it possible to produce a toothpaste that can have (1) suitable consistency for dispensing from tubes and dispensers and (2) high stability against changes in consistency during storage.
Finally, an object of the present invention is to find a toothpaste which, by virtue of its overall composition, can satisfy to a high degree the various demands made of a modern dental care preparation.